Process of newsprinting



Patented Mar. 26, 1940 UNITED STATES 2,194,911 raoorss or NEwsramrmGPhilip'K. Porter, Jackson Heights, N. Y., a'ssignor to InterchemicalCorporation, New York, N. Y

a corporation of Ohio Application January 15, 1938, Serial No. 185,158

No Drawing.

6 Claims. (Cl. 101-416) This invention relates to the art ofnewsprinting and provides a method in which printing ink applied rapidlyto porous paper is set or dried by controlled penetration.

In the extremely rapid printing required in printing newspapers, it isnecessaryto rely on penetration of the inkvehicle into porous paper toset or dry the ink. The rapidity with which the ink must be transferredfrom'the printing 10 roller to the paper determines the viscosity of theink which must be used and in general requires an ink of low viscosity.The penetration of the ink vehicle into the porous paperjwhich ingeneral varies inversely to the viscosity, is entirely uncontrolled.Consequently, the initial penetration is sometimes insuflicient to drythe ink before the web is rolled up so that oifsetting occurs, and, innearly all cases, the penetration continues for a considerable periodboth downwardly into the paper and outwardly from the printed letters,frequently causing the print to be visible on the back side of the sheetand making the print more or less fuzzy onthe front side.

My invention overcomes these difllculties by controlling the penetrationof the ink into porous paper in newsprinting. In accordance with myinvention, the viscosity of the ink on the print is varied so as tocause a rapid initial penetration followed by an arresting of the pene-'tration: As a result, I obtain even more rapid 'drying than iscustomarily obtained by penetration in newsprinting, and at the sametime avoid the disadvantages of fuzziness and striking through whichresult from too great penetration.

In carrying out my invention, a low viscosity printing ink, preferablycontaining a thermoplastic binder is applied to a highly porous paper ofthe type known as newsprint paper. The viscosity of the ink on the printis momentarily recosity which the ink reaches in the third step must beconsiderably higher than the viscosity which the ink has when applied tothe paperin the first step. This result may be attained by cooling theprint to a temperature considerably below the temperature at which theink is applied to the paper, or more conveniently by evaporating aportion of the liquid in the ink vehicle durin the second step of themethod, so that, on cooling the ink to its original temperature, itcontains a larger'proportion of binder than it did originally, and is,therefore, more viscous. For this reason, it is desirable that the heatapplied momentarily to cause the initial penetration be suflicient tocause evaporation of at least a 'minor I part Of the liquid in the ink.

duced by heat to cause rapid penetration, andinitial penetration willvary, depending on the speed of printing. For the highest printingspeeds, of 1500-1800 feet per minute, a viscosity range of from two toeight poises at printing temperatures has been found desirable; whileviscosities up to a limit of about 20 poises are satisfactory for theslower speed printing (800-1000 feet per minute) used in printing thetypical colored newsprint.

Any ink may be used which prints in a satisfactory manner, and whichbecomes much more fluid when exposed to heat; for the preferred practiceof my invention, the ink should 'lose some of its solvent during theheating operation.

Typical inks which are satisfactory include the following:

Viscosity, 3.8 poises at 30 C.

EXAMPLEII Parts by weight Carbon black 11.25 Gilsonite 12.5 Methylviolet toner 2.0 Induline toner 2.0

Ink oil (viscosity 100 seconds Saybolt at 100 c.) 62.25 Petroleum oil(boiling range 202-264 C.) 10.00

Viscosity, 3.9 poises at 30 C.

This ink, unlike the last, contains a very large percentage of ink oilwhich is non-volatile even at elevated temperatures. However, this inkoil has such slight solvent action on the resin that 1 comprisesapplying by conventional relief printafter the more volatile solvent isevaporated during the heating step, and the ink has cooled, theviscosity becomes very high and further penetration is blocked. Inks ofthis type may be used which only lose a very small percentage of solventby evaporation.

Either of the above inks may be applied in a news press to a web ofnewsprint paper traveling at a speed of about 1,800 feet per minute.

Each portion of the printed web is momentarily heated to a temperatureof about 400-450 F., to reduce the ink to a very thin consistency andcause it to penetrate rapidly into the porous paper. The heat also hasthe effect of-evapcrating a minor proportion (about 25%) of the liquidpetroleum fraction in the ink. Such heating may conveniently be effectedby passing the web as it leaves the printing roller through an oven 6 or8 feet long, heated to a temperature of the order of 1000-2000 F., sothat each part of the web is exposed to this temperature for about onequarter of a second.

Each portion of the web, after it has been heated, is cooled immediatelyto approximately room temperature (25 C. or less). This increases theviscosity of the ink well above its original viscosity and stops furtherpenetration of the ink. The cooling may most conveniently be eflected bypassing the web over a chilled metal roller immediately after it leavesthe oven.

Other modes of carrying out the invention may obviously be used withoutdeparting from the spirit of my invention.

. What I claim is:

1. The improvement in newsprinting, which comprises applying a lowviscosity press stable printing ink containing a thermo-plastic binderand a volatilizable liquid to a highly absorbent paper by conventionalrelief printing, momentarily heating the ink on the paper sufllcientlyto cause rapid absorption thereof into the paper, and to causeevaporation of a portion of the liquid, and thereafter coolin theevaporation of liquid being sufllcient to raise the viscosity of the inksumciently after cooling so that further movement of the ink through thepaper is substantially arrested.

2. The method of claim 1, in which the heat is sufficient to evaporateat -"least 25% of the liquid. v

3. The improvement in' newsprinting, which ing to a highly absorbentpaper a low-viscosity press stable printing ink containing athermoplastic resin dissolved in a mixture of a relatively non-volatilesolvent of low solvency and a relatively volatile solvent of highsolvency, momentarily applying sufllcient heat to the ink on the paperto reduce its viscosity and cause it to penetrate rapidly, and toevaporate solvent of high solvency, and thereafter cooling the ink, theevaporation of high solvency liquid being sufficient to raise theviscosity of the ink sufficiently so that after cooling further movementof the ink through the paper is substantially arrested.

4. The improvement in newsprinting which comprises applying, byconventional relief printing, a press-stable ink containing avolatilizable solvent and having a. viscosity of from 2 to 8 poises atprinting temperature to a web of highly absorbent paper travelling at aspeed of at least 1500 feet per minute, heating the web after printingby exposing each portion thereof to a temperature of the order of 1000to 2000 F. for a fraction of a second, whereby the ink is absorbed intothe paper and a portion of the solvent is evaporated, and immediatelycooling the web, whereby the viscosity of the ink is increasedsumciently to substantially arrest further movement of the ink throughthe paper.

5. The improvement in newsprinting, which comprises applying, byconventional relief printing, a press-stable ink containing avolatilizable solvent and having a viscosity of from 2 to 20 poises atprinting temperature to a web of highly absorbent paper travelling at aspeed of at least 800 feet penminute, heating the web after printing byexposing each portion thereof to a temperature of the order of 1000 to2000 F. for a fraction of a second,'whereby the ink is absorbed into thepaper and a portion of the solvent is evaporated, and immediatelycooling the web. whereby the viscosity of the ink is increasedsufficiently to substantially arrest further movement of the ink throughthe paper.

6. The method of printing which comprises applying a low viscosity pressstable printing ink to a highly absorbent paper by conventional reliefprinting, momentarily heating the applied ink sumciently to cause rapidabsorption thereof into the paper and to so change the ink that itsviscosity at ordinary room temperature is so increased that on coolingfurther movement of the ink through the paper is substantially arrested,

and thereafter cooling the paper.

PHILIP K. PORTER.

